Photophysical behaviors of a shape-persistent zinc porphyrin organic cage

Abstract

A pair of chiral metallic porphyrin cages, (R)/(S)-PTC-1(Zn), have been afforded by pure chiral cyclohexanediamine reacting with the zinc 5,15-di[3′,5′-diformyl-(1,1′-biphenyl)]porphyrin. Both their chiral tubular structures have been demonstrated via single crystal diffraction and circular dichroism studies. In addition, the photophysical behavior of the metallic organic cage, in combination with the monomeric reference zinc 5,15-di[3′,5′-cyclohexyliminomethyl-1,1′-biphenyl]porphyrin (ZnCBPP), has been systematically explored by using UV-vis, fluorescence and transient absorption (TA) spectroscopy in solution. TA data disclose that PTC-1(Zn) possesses a much longer triplet lifetime than monomer ZnCBPP. In addition, the homogeneous system of the cage enables the production of more singlet oxygen than the monomeric compound according to 1,3-diphenylisobenzofuran photodegradation, ESR spectroscopy and aerobic oxidation of benzylamine under visible light irradiation.